<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="./ctrip_join.js"></script>
    <style>
        * {
            margin: 0;
            padding: 0;
            list-style: none;
        }
        
        .a {
            width: 500px;
            height: 400px;
            background-color: aqua;
            margin: 20px auto;
        }
        
        #ul {
            width: 40px;
            height: 180px;
            position: absolute;
            top: 30px;
            left: 160px;
        }
        
        .lis {
            width: 40px;
            height: 40px;
            background: url('https://pic.c-ctrip.com/platform/online/home/un_icon_leftnav.png');
            background-repeat: no-repeat;
            background-position: 0px 0px;
        }
        
        .lis_a {
            color: #fff;
            text-align: center;
            line-height: 40px;
        }
    </style>
</head>

<body>
    <main>
        <section class="a"></section>
        <section class="a"></section>
        <section class="a"></section>
        <section class="a"></section>
        <section class="a"></section>
        <section class="a"></section>
        <section class="a"></section>
        <section class="a"></section>
        <section class="a"></section>
        <div>
            <ul id="ul"></ul>
        </div>
    </main>
</body>
<script>
    ul.innerHTML = cb_join.map(item => {
        return `<li class='lis'>${''}</li>`
    }).join("");
    ul.children[0].className = 'lis lis_a';
    ul.children[0].innerHTML = cb_join[0];
    ul.children[0].style.background = "url('')";
    [...document.querySelector('#ul').children].forEach((item, index) => {
        item.style.backgroundPosition = `11px ${'-'+40*index+'px'}`
    })
</script>

</html>